The invention relates to an anti-locking brake system (ABS) and, more particularly, to an hydraulic anti-locking brake system that uses an hydraulic circuit and an electric control unit to respectively control the braking force of the front and rear wheels.
When a motor-driven vehicle is braked, if the brake system is not adequately designed, the control of the braking force may be insufficient and the wheels may be locked, causing dangerous sliding of the vehicle. Therefore, in order to overcome the above problem, anti-locking brake (ABS) systems have been developed.
Anti-locking brake systems generally use a single braking control signal, a pressure motor, a system of single oil circuit, a control unit, and an hydraulic structure of four wheels and eight electromagnetic valves. By comparing the respective velocities of the four wheels of, for example, a car, a vehicle velocity is consequently evaluated. By comparing the vehicle velocity and each wheel velocity, an adequate amount of pressure increase and pressure release is consequently supplied to the system. Hence, when the driver presses on the brake pedal, a braking signal is outputted to activate the ABS system. When a wheel velocity is lower than the vehicle velocity, a sliding effect thus occurs. The oil output vales of the electromagnetic valves are consequently opened so as to reduce the braking pressure. Oppositely, if a wheel velocity is higher than the vehicle velocity, the vehicle thus has an insufficient braking force. The oil input valves of the electromagnetic valves are opened so as to increase the braking force. The above operations are repeated until the brake pedal is released or the vehicle is stopped. Because the above traditional system only has a single braking control signal and a system of a single oil circuit, each wheel therefore has substantially a same braking force. However, because the respective configuration of each wheel is different from one another, the application of a same braking force to each wheel therefore does not provide the optimal braking conditions. Furthermore, because the wheel characteristics are different from one wheel to another wheel, the comparison of the vehicle velocity with the wheel velocity to determine a pressure increase or pressure release therefore needs to be effected with respect to each wheel to provide adequate regulation.
Accordingly, it is therefore a principal object of the invention to provide an hydraulic anti-locking brake system for a motorcycle that uses two braking control signals, a pressure motor, and an hydraulic structure of two wheels and four electromagnetic valves. Thereby, the respective braking forces of the front wheel and rear wheel can be separately or simultaneously controlled. Thus, optimal braking forces can be obtained.
To attain the above and other objectives, an hydraulic anti-locking brake system for a motorcycle of the invention comprises two hydraulic circuits respectively installed on a front wheel braking lever and a corresponding front wheel brake, and between a rear wheel braking lever and a corresponding rear wheel brake. Each hydraulic circuit comprises a pressure compartment with at least a piston, a pressure increasing circuit, and an electric control unit. The pressure compartment has an oil outlet, and the piston is connected to one of the front or rear wheel braking levers. The pressure increasing circuit includes an inlet terminal and an outlet terminal, the oil outlet of the pressure compartment being connected to the inlet terminal of the pressure increasing circuit. The pressure releasing circuit is connected between the outlet terminal of the pressure increasing circuit at one end, and the oil outlet of the pressure compartment and the inlet terminal of the pressure increasing circuit at another end. The pressure releasing circuit is further connected to a motor. The electric control unit comprises a front wheel velocity sensor, a rear wheel velocity sensor, a slip rate calculator, a slip rate comparator, a front wheel controller and a rear wheel controller. From the velocity values sensed by the front and rear wheel sensors, the slip rate calculator determines the velocity of the motorcycle and slip rates of the front and rear wheels. From a plurality of control zones of slip rate parameters established in the electric control unit, the slip rate comparator determines in which control zone the calculated slip rates of the front and rear wheels are located. Respective signals are consequently outputted to the front and rear wheel controllers that consequently control the operations of the motor, pressure increasing circuit, and pressure releasing circuit. Via the operation of the braking levers, an actuation of the piston is thereby activated to provide hydraulic pressure. According to a variation of the calculated slip rates of the front and rear wheels, different signals hence are further outputted to control the pressure increasing circuit and the pressure releasing circuit so as to adequately regulate the braking hydraulic pressure.
To provide a further understanding of the invention, the following detailed description illustrates embodiments and examples of the invention, this detailed description being provided only for illustration of the invention.